Q.

The barrier potential of a pn junction depends on
(1) type of semiconductor material
(2) amount of doping
(3) temperature  
Which one of the following is correct                                  [2014]

1 (1) and (2) only   
2 (2) only  
3 (2) and (3) only  
4 (1), (2) and (3)  

Ans.

(4)

The barrier potential depends on type of semiconductor (For Si, Vb = 0.7 V and for Ge, Vb = 0.3 V), amount of doping and also on the temperature.